The present invention relates to an injector for delivering gases to a surface and to a deposition chamber for processing a substrate. More particularly, the invention relates to a single body injector and to a deposition chamber having an integrated single body injector for processing a semiconductor substrate by chemical vapor deposition (CVD). The invention also relates to a method of fabricating a single body injector and deposition chamber.
Chemical vapor deposition (CVD) is a critical component in semiconductor manufacturing. CVD occurs when a stable compound is formed by a thermal reaction or decomposition of certain gaseous chemicals and such compounds are deposited on a surface of a substrate. CVD systems come in many forms. One apparatus for such a process comprises a conveyorized atmospheric pressure CVD (APCVD) system which is described in U.S. Pat. No. 4,834,020 and is owned by assignee. This patent is incorporated herein by reference. Other CVD apparatus may be used such as plasma-enhanced CVD (PECVD) systems, and low pressure CVD (LPCVD) systems.
Important components of a CVD system include the deposition chamber where deposition occurs, and the injector utilized for delivering gaseous chemicals to the surface of the substrate. The gases must be distributed over the substrate, so that the gases react and deposit an acceptable film at the surface of the substrate. The deposition chamber must be carefully designed to provide a controlled environment in which deposition can take place. For example, the chamber must provide gas confinement, but reduce recirculation of the gases which can cause pre reaction of the gases and the deposition of a non-uniform film. The chamber must provide exhausting for the elimination of excess reactants and reaction by-products, yet not disrupt the flow of gases to the substrate for reaction. Moreover, the temperature of the chamber and its components must be carefully controlled to avoid condensation of reactant gases, minimize accumulation of byproduct dust and enable cleaning of the system. Additionally, the deposition chamber should preferably maintain mechanical integrity (such as tolerances) throughout its operation. All of these factors must be carefully balanced to provide a proper environment for deposition.
A function of the injector in such a deposition chamber is to distribute the gases to a desired location in a controlled manner. Controlled distribution of the gases maximizes the chance of complete, efficient and homogeneous reaction of the gases, in part by minimizing pre-mixing and prior reaction of the gases. A complete reaction provides a greater opportunity for a good quality film. If the gas flow is uncontrolled, the chemical reaction will not be optimal and the result will likely be a film which is not of uniform composition. When the film is not of uniform composition, the proper functioning of the semiconductor is impaired. Thus it is important that an injector design facilitates the desired flow of the gases in a controlled manner.
In a prior art injector, owned by the assignee and described in U.S. Pat. No. 5,136,975, a number of stacked plates each including a number of linear hole arrays is utilized. The plates produce a number of cascaded hole arrays and a chute surrounded by a cooling plate is positioned beneath the last hole array. The chute includes a central passage and ducts are formed between the chute and the cooling plate. Chemical lines deliver gases to a top plate which discretely conveys the gases to the top of individual cascaded hole arrays. The gases are fed through cascaded hole arrays which cause the gas to flow in an increasingly uniform manner. The chute passage receives the gases individually and then conveys the gases to a region above a wafer. In this region, the gases mix, react and then form a film or layer on the wafer.
The cascading action described above provides an uniformly distributed gas flow. However, flow control and simplicity of injector design can be improved. Further, the integration of the injector into the deposition chamber can be considered. Often, in prior art systems the injector is inserted into the deposition chamber, and sealed with a separate frame. The exhaust and purge arrangement, and temperature control systems add further mechanical components to the chamber. All of these components introduce mechanical complexity into the design. Additionally, the requirement for seals to mate all of these components makes temperature control of the component surfaces more difficult, and increase maintenance costs and downtime of the system due to their deterioration from exposure to eroding environments. Thus it is desirable to provide a deposition chamber that minimizes the aforementioned problems.
It is an object of this invention to provide an improved deposition chamber for processing of semiconductor substrates.
It is a further object of this invention to provide an improved injector for delivering gaseous chemicals in a controlled manner to a surface for depositing films or layers on the surface by chemical vapor deposition (CVD).
It is additionally an object of the present invention to provide a deposition chamber having an integrated injector.
Another object of this invention is to provide an injector fabricated from a single block of material, thereby eliminating complicated machined parts requiring precision alignment and positioning.
A further object of this invention is to provide an injector free from internal seals, thereby minimizing maintenance and associated costs.
Another object of the present invention is to provide a deposition chamber that minimnizes the number of components and seals thereby reducing maintenance and downtime costs.
A further object of the present invention is to provide an injector and exhaust system in which the temperature of all surfaces exposed to the reacting gases may be accurately controlled.
A related object of this invention is to provide a deposition chamber and injector which improves the uniformity of films deposited on wafers.
These and other objects are achieved by the injector herein disclosed comprising an elongated member with end surfaces and at least one gas delivery surface extending along the length of the member and which includes a number of elongated passages formed therein. Also formed within the member are a number of thin distribution channels which extend between the elongated passages and the gas delivery surface. In another embodiment of the invention a number of metering tubes may be inserted into each elongated passage and are spaced from the walls of said passages and extend between the ends. The metering tubes may contain openings of varying form and dimension which may be directed away from the distribution channels. The metering tubes receive a gaseous chemical which is conveyed along the metering tubes, whereby the gas flows out of the openings, and is conveyed through the corresponding distribution channel and is directed in a substantially controlled manner along the length of the gas delivery surface. In the instance where a number of gases are employed, the distribution channels direct the distribution of such gases to a region where mixing of the gases is desired. In addition the distribution channels prevent chemical fouling of the injector by preventing premature chemical reaction of the gases. The gases are directed to a desired region where they mix, react and form a uniform thin film on the substrate positioned beneath the injector.
In an alternative embodiment an injector is provided which further contains an elongated passage for receiving an etchant species. The etchant species is conveyed to the gas delivery surface via at least one distribution channel which extends between the elongated passage and the gas delivery surface. The etchant species is distributed along the gas delivery surface where it removes deposited materials along the gas delivery surface and other surfaces within the chamber.
In another alternative embodiment an injector is provided comprising an elongated member with end surfaces and at least one gas delivery surface extending along the length of the member and which includes a number of first elongated passages formed therein for received a gas. The gas delivery surface contains rounded side regions and a center recessed region. Also formed within the member are a number of thin distribution channels which extend between the first elongated passages and the center recessed region of the gas delivery surface. In another embodiment, the injector further includes at least one second elongated passage formed therein for receiving an etchant species. The etchant species is conveyed via at least one thin distribution channel which extends between the second elongated passage and one of the rounded side regions of the gas delivery surface. As described above, metering tubes may be inserted into each elongated passage and are spaced from the walls of said passages and extend between the ends.
Of particular advantage, the invention further provides for an inventive deposition chamber. The deposition chamber includes an injector comprised of a single member having end surfaces and at least one elongated gas delivery surface extending along the length of the injector for delivering gases to the substrate; a plurality of vent blocks having end surfaces and at least one elongated external surface extending along the length of each of the vent blocks; and a support positioned beneath the injector and vent blocks, creating a deposition region therebetween. The vent blocks are positioned adjacent one on each side of the injector, and spaced from the injector to define exhaust channels therebetween for removing the gas.
In an alternative embodiment, a deposition chamber is provided that is comprised of multiple injectors and vent blocks